1. Field
This application relates generally to virtual reality ride systems, and, more specifically, to methods and systems using low-frequency vibrations to reduce motion sickness caused by virtual reality.
2. Description of the Related Art
Virtual reality is a computer-simulated environment that can simulate a user's physical presence in real or imaginary environments. A virtual reality environment may include visual images displayed either on a computer screen or through a stereoscopic (e.g., 3D) display, such as a wearable headset. The virtual reality environment may also include sound provided through speakers or headphones and force feedback via, for example, a dynamic platform or a vibrating controller or joystick. Applications of virtual reality include medical, gaming, and military environments.
Although virtual reality systems may provide a realistic and immersive experience, they also cause motion sickness in many users. Motion sickness may occur when the systems of the body responsible for balance do not agree with each other. The three bodily systems primarily responsible for balance are the visual system (including the eyes), proprioception (the sense of movement and relative position of various parts of the body by the musculoskeletal system), and the vestibular system located in the inner ear. The vestibular system includes three semicircular canals and two otolith organs. The canals are oriented in three spatial planes and sense angular acceleration, while the otolith organs sense linear acceleration and the position of the head relative to gravity. The brain combines information from proprioception and from the vestibular system into its overall sense of body position, movement, and acceleration. Visual signals regarding the body's position in relation to its surroundings are processed by the brain and compared to information from the vestibular and musculoskeletal systems.
Visually induced motion sickness occurs when motion is perceived visually but the body is physically at rest, is not feeling forces from acceleration, or is not physically experiencing motion consistent with the visually perceived motion. When this happens, there is a disconnect between the motion perceived by the visual system and the physical motion (or lack thereof) sensed by the proprioception and the vestibular systems. A person may experience visually induced motion sickness when, for example, viewing a first-person perspective of a moving scene, such as in a video game or a flight simulator.
Motion sickness caused by computer images, video games, simulators, or virtual reality may be referred to as simulation sickness. Simulation sickness is typically associated with situations in which a person generally is not moving, which distinguishes it from other types of motion sickness that occurs when a person is in motion (e.g., car sickness or sea sickness).
Symptoms of motion sickness may include dizziness, fatigue, nausea, headaches, drowsiness, sweating, and vomiting. Moreover, motion sickness may be even more severe during a virtual reality experience in which all external reference points that could provide a frame of reference are blocked from vision and the simulated images are 3D, such as when a 3D headset is used.